Multipiston meter



Maly 3, 1938-. F. HEJDUK Er AL l r2,116,265 MULTIPISTON METER Filed Dc.2e. 1934l 4 Sheets-Sheet 1 ZJ if MKM,

May 3, 1938. F. HEJDUK ET AL 251162265 MULTIPISTON METER Filed Dec. 26,1934 Y l4 Sheets-Sheet I2v I1 LT'g Jazz jlfeafzzafz 2z l 4 May s, 193s.F. HEJDUK ET AL 2,116,265

MULTIPISTON METER Filed Decf 2e, 1954 4 sheets-sheet s Alza me] Y May 3,193.8. F. HEJDUK ET AL 2,116,265

MULT IPI STON METER Filed Deo. 26, 1934 4 Sheets-Sheet 4 Patented May 3,1938 MULTIPISTON IVIETER Frantick Heiduk and Jan Neumann, Prague,Czechoslovakia Application December 26, 1934, Serial No. '159,293 InCzechoslovakia December 2?.'1, 1933 V8 Claims. The subject of theinvention is a volumetrically working multi-piston meter suitable foraccurate- 1y measuring liquids having a small viscosity.

The object of the invention is to provide a 5 meter for obtaining thehighest accuracy `of measurement at `various flow speeds andpermanentmaintenance of this accuracy.

inaccuracy of measurement which Aoccurs at different speeds of flow ofliquid is due chiefly to i` i lack of tightness of the distributor andmeasuring devices. The leakage due to lack of tightness depends, underotherwise equal conditions, von the one hand on 4the loss of 'pressurein the meter which increases with the* increase oi the passiveresistance, and on the other handy on the size of the contact surfacesof the distributor device. Accuracy of measurement is moreover dependenton the perfectly shock-free cooperation of all the devices, that is,upon the elimination of mechanical and hydraulic shocks inthe measuringapparatus.

Inac'curacy of measurement which occurs after a considerable period ofuse, is due to` the wear of the metering members or to such a wearof thedistributor device as will result in a deterioral tion of the tightjoint between its parts. As regards wear, there is the tendency todimension the metering members so that they practically show no wear atall, and in dimensioning the distributor devices so that theirfrictional resistance and speeds of movement are. as low asvposslblewhereby favourable conditions for little wear are produced.

According to the new invention, the named oblject is attained by aparticular construction of some meter parts, the action of which is dueto their mutual inter-dependence. The whole meter is thereby improved toa considerable degree. In the rst instance, there is the distributorvalve which should have a smalldiameter and should be relieved from loadas far as possible, in order to have a small resistance only. Inconnection therewith, short closing edges, small pressure per squareunit of surface, small peripheral velocity and small and uniform wearwill result. The valve has, moreover, the advantage that it enables thecrank chamber to b e completely separated from the flowing liquid andpermits the use of almost rectilinear and 4very short inlet and ismoreover a., 'antageous as regards the dis-- charge of air accidentallyentering from the metering space. 1 ,Y

- `As previously mentioned, `the metering parts must not be subjected toweanmore particularly outlet passages for the liquid. This constructionY(Cl. 'Z3-247) wear which might cause an alteration of the piston stroke.In cases in which the stroke is directly limited by the crank mechanism,this condition is not fullled, inasmuch as the parts" of the crankmechanism are always subjected to wear. 5 But even with constructions inwhich the pisto'n hub is limited'by iixed abutments, there occurs acertain, although substantially lesser, wear owing to the knocks uponthe contact surfaces occurring particularly with large apparatuses. Thedamping of the piston movement which is already produced in the endpositions by the distributor valve, is not suilicient, and the inventionprovides for the damping of shocks by mechanical and hydraulic' meanstothe highest degree. The 15 crank mechanism .of the meter having,stroke limitation of the pistons by abutments serves only for actuatingthe distributor and the counting device and for the mutual movementconnection of the two piston units in the usual four-piston type ofmeter, but it must be possible to vary the piston stroke for obtainingaccurate measurement.

For this reason a small play isvleft between the crank and thecorresponding cross guideways or slots in the yokes connecting opposedpistons. However, shocks of a secondary order are caused by this play,which may, 'in alesser degree, influence the accuracy and the permanenceof the measurement. For this reason the invention also provides for aconstruction of a meter crank which will avoid such shocks.

One constructional example of the invention is shown in the accompanyingdrawings.

Fig. 1 is a vertical section through the complete four-piston meter,taken through the axis of two cylinders,

Figs. 2 and 3 are views of the seat and the l valve,

Figs. 4 and 5 show cross-sectional views of other constructions ofdistributor valves,

Fig. 6 is a cross-sectional View of the damping device in the cylindercover,`

Fig.l 'l is a cross-sectional view of a device employing the ydampingabutment for taking samples of the measured liquid,

Figs. 8 and 9 show a construction shaft.

Fig. 10 is a cross-sectional view of the valve showing the forces andmoments caused by the pressure of the liquid actingon the surfaces of 50the valve. Fig. 11 is a plan view of the valve showing the differentareas acted on by the pressure of the liquid.

The casing of the meter according to Fig. 1 contains four workingcylinders I arranged in 55 v l of the crank I pairs, each. pair alwayshaving commonaxes,

both axes being at right angles to each other and intersecting in thevertical main axis of theq meter. In each cylinder, is provided a piston2, two such pistons, having the same axis, being connected by yokes 3and 3' having cross guideways. In these cross guideways of the yokes 3,3', Fig. 9, move rollers l, 4' mounted upon a pin 5, said pin beingfixed in a double crank 8, which latter turns as a whole about a pivot 6inserted into the lower cover 1. The pivot 6 rotates during itsmovementthe crank shaft 9.

Above each cylinder is arranged a passage 'I6 through which liquidenters and leaves the meter cylinders and the cylinder ends are closedby means of the covers. I'I into which are arranged adjustable abutmentmembers I8. All the four passages I6 terminate in a fiat seat I2 in fouropenings I5, Figs. 1 and 2, concentrically and as close as possible tothe crank shaft 9 so that the diameter of the valve seat I2 becomes assmall as possible. Upon the seat I2 rotates the distributor valve I Ilwhich is keyed upon the mentioned shaft 9. The valve has generally theshape of a truncated cone and in its lower bearing surface II, Fig. 3,there are two ports I 3- and I4. The port I3 serves for the inlet of theliquid and the port I 4 for the outletof the liquid from the meteringcylinders. 'Ihe inlet port I3 is connected by the duct I9 which isentirely separated from the remaining valve space, with the port in theconical wall of the slide. The outlet port Il is directly connected withthe concentric circular port at the upper end of the valve I0. The spacearound the slide is closed by the cover 2U, which latter is providedwith the inlet socket2I and the outlet socket 22 separated one from theother by a partition wall 20' having a circular aperture 20". Thepartition wall 20' is arranged to provide a chamber, around the outersurface of the valve I0, connected to the duct I9 of the inlet port I3.vIn order to obtain tightness during the passage of the metered liquidfrom the rotating valve I0 into the stationary outlet socket 22, a ring23 is provided at the upper end of the valve, which is held by anelastic and tight diaphragm 24 in the proper bearing position, the twoparts I0, 23 being connected together'by a few pins 25 of tombac, forexample, which permit of an axial displacement. The pins 25 permit axialdisplacement of the valve parts I0 and 23 while at the same time theyprevent torsional movement and angular displacement between these parts.The ring 23 moves upon an annular face 26 surrounding aperture 20" ofthe cover 20 and may be further pressed against the lattery by asuitable, not illustrated springbeing analogous to the spring 3l in Fig.4. The metering movement is transmitted to the corresponding,

,Y only partly illustrated, counting device 60, lby

means of a carrier member 21 and a shaft 28, aid member 21 engaging alug 21' on the valve The described apparatus works as follows:-

The liquid enters through the inlet socket 2I, the duct I3 of the valveand from the latter through the port I3 in the valve seat and thenthrough the corresponding passage I 6 into the corresponding workingcylinder I. The simultaneous outflow of. liquid from the oppositeworking cylinder takes place through the corresponding passage I6 andthe port I5 in the seat I2 and then through port I4 into the space 29 ofthe valve I0, where the liquid IOWS through the 'centre of the valve andthrough the ring 23 in the upper cover portion 20, and from therethrough the outlet socket 22. The pressure of the liquid acting on thepiston 2 causes this piston to move in the inward direction. Thismovement is accompanied by the rotation of the distributor valve I 0since this valve isconnected ,by 'means of a crank mechanism to thepiston 2. During this rotation this valve closes the.l flow of liquid tothe i'lrst cylinder, that is the cylinder associated with the piston 2,and simultaneously the inlet to the next cylinder is opened whereby thepiston in this latter cylinder is pushed inwardly through the action ofthe liquid; By turning the valve through degrees the entrance to theilrst cylinder is completely closedgwhile at the same time the port I3of the valve is brought into the registration with the port I5 of thesecond cylinder. By turning thevalve through 90 degrees the inlet to thesecond cylinder is fully opened and by. turning the valve throughdegrees the liquid pressure is caused to act upon the piston opposite tothe rst piston.

Although the essence of the invention has been explained in connectionwith a four-piston meter With horizontal cylinders, it is possible toapply the invention to meters with a diiferent number of cylinders and adifferent arrangement of cylinders, Without altering thereby the essenceof the invention.

In Fig. 4 is shown a modied construction of the distributor valve whichis so designed that the ring 23' is connected with the valve I0 by meansof a thin-walled corrugated tube 30 of tombac, for example, soldered onat both ends. 'Ihe valve thenconstitutes a single metallic member, theelastic connection between its contact surfaces being maintained. 'Ihefiat spring 3I insures both slide faces bearing against theircorresponding seats. 'I'he corrugated tube 30 which is attached to thering 23' and the valve part I0 permits the ring 23' and the valve partI0 to move axially with respect to each other and at the same timeprevents torsional movement between the ring and the valve part I0. Thespring 3| presses the ring 23' away from the valve part I0 and maintainsthis ring and the valve part I0 against their respective seats.

Fig. 5 shows a further construction of the valve in which the latterconsists of one piece, the upper end I0' being tubular and guided in agland, which latter insures tightness along the cylindrical surface.

In Fig. 5 an example of such a gland aii'ording small resistance duringthe rotation is given. Tightness is attained by means of a thin leathercup 32 which is xed to cover 20 by means of a ring 33 secured to cover20 and is pressed by a helical spring 3l arranged in a recess 35 of thecover 20, against the side of the valve I0, I0 along which tightness isto be maintained.

In order that the valve should answer in the most perfect manner thepreviously mentioned requirements. that is, should oier a minimum audaceand the moment of the surface of the diameter d multiplied by p2 and thearm must be greater than half of the surface of diameter D multiplied bythe pressure p1 and the arm 5D and half of the surface of diameter Dmultiplied by the pressure p2 and the arm 135D.

For purposes of explanation, the values of the arms D and gD wereobtained by assuming 31r equal to 10.

This may be more clearly brought out as follows in conjunction withFigs. and 1l in which the relative dimensions of the valve -III areshown:

D=the largest valve diameter on the lower seating surface.

d=rthe outer diameter of the upper annular base surface. I

The minimum diameter of d is governed by the condition that thecross-sectional area of an opening of diameter d is equal to thecross-sectional area of one of the openings I3 or I4 so that itpossesses a suilicient ow cross-section. The greatest value of thediameter d would be when this diameter is equal to the diameter D, thatis, when the valve shape is that of a cylinder. When a greater pressureprevails onthe exterior of the valve than on the interior, then it isobvious that in the case where d is aminimum, the valve will be forcedupon its lower seat with a relatively large force. On the other hand,when d is equal to D the tendency of th forces acting on the valve is tolift it von the side of the inlet opening. The optimum value for thediameter d may be determined by the following procedure. In order thatthe calculation shall not become too complicated owing to the inuence ofentirely subordinate factors, the following assumptions are made. It isassumed that the pressure p1 acting on the exterior of the valve, asshown in Figure 10 is greater than p2 acting' within the valve, by apressure represented by Ap2, which represents the pressure loss in themeter. The transition of the pressure from p1 to p2 is assumed to occurat the outer side of the valve and is based on the radius NID.

Finally it is assumed that the pressure p1 acts against halfof the lowersurface of the valve and the pressure p2 acts on the other half. Thisassumption is possible when the valve moves against four openingswhichin generalform a the excess pressure pl-pz may amountto als of akilogram per square centimeter.

The equilibrium of the forces and moments around the axis A at adistance of y from the valve axis is given by the following calculationsin which P1 is equal to DI-dz) T 4 pl.

81nd l In o'rder that the valve shall not become lifted the side ofopening I5 (which excess pressure is exerted approximately beneath halfof the lower valve resting surface) the resulting moment of force whichacts on the valve must press the/same against its seat. This requirementis achieved by selecting a proportionately smaller diameter d withrespect to -D and this then governs the shape of the distributing valve.The most undesirable case occurs when the inlet opening of the valvebecomes located symmetrically beneath the rib between two channels inthe seat beneath the valve. In this case the inlet pressure of theliquid p1 acts from beneath upon the rvalve to the extent of `half itssurface and the second side is acted upon by the outlet pressure p2.

' In order that the valve shall not lift, the sum of the momentsoriginating from the circular surface of diameter D-d multiplied by thepressure p1 and the arm and those of the surface of diameter dmultiplied by p2 and the arm must be greater than half the surface ofdiameter D multiplied by the pressure p1 and the arm if I and half thesurface of diameter D multiplied by the pressure p2 and the arm `Thisequation gives the diameter as The force of the spring also has aninfluence on the diameter d, said spring forcing the valve to its lowerseat. In the case of greatest spring force (as shown by experience andobservation) the diameter d may be increased up to about 25% so that thegiven equation takes the following form:

It is known from the Varignon law that the moment of a resultant forceis the sum of the moments of all the lateral forces and that it ispossible to add to a moment unless we should destroy the equilibrium oftwo other moments ,which are equivalent but of opposite direction.

It would be very difficult to find for the force P1 the center of areaof the surface when the part of the port I3, shown sectioned in Fig. 11,is subtracted. 'I'he same diiculty loccurs during the computation of thecenter of area, for the force Pa, of the semi-circle when the same partof horizontal projection of the port I3 is deducted.

As the moments of these surfaces, on which is acting the same liquidpressure, are of the same value but of opposite direction,themathematical computation is facilitated by adding to the actualmoment of force P1 the moment of thehorizontal projection of the portI3, acting downwards. The actual moment of the force P3 and the samemoment is taken as acting upwards. By this way the computations arefacilitated without making any fault or inaccuracy.

The same consideration takes place during the computations of themoments from the forces P2 and P4 and a moment of the surface I4 of Fig.1l, equal to the horizontal projection of the port I4 is added. 'Ihusthe calculation could thereafter be executed as if the ports I3 and I4were not A present.

The valve I according to the present invention permits of the outflow ofliquid occurring through its upper surface in the upward direction andnot in the downward direction through the crank chamber as was hithertomostly the case. By the separation of the crank space from the flowingliquid further advantages are attained. No impurities carried by themetered liquid can reach the enclosed crank mechanisms. Moreover, nopassage of the liquid due to leakage around the piston can take placebetween the metering space of the cylinders, into which the alreadymetered liquid ows, as is the case with meters in which the meteredliquid flows out through the crank chamber. The closed crank chamber canmoreover be filled with a liquid which lubricates the crank mechanismand preserves the packing cups of the pistons.

Fig. 6 shows on a larger scale the damping device of Fig. l for dampingthe movement of the piston before its extreme dead centre. 'I'he dampingis here a double one, namely, by means of a spring and hydraulic. Theabutment I8 is here constructed asa bolt which is provided at one endwith a tube 36 connected therewith by means of ribs. The tube passestightly through a plate 31 which is secured between the cylinder and thehead I1 and separates completely the cylinder space from the inlet andoutlet passage. The bolt I8 is inserted into a hollow screw 38 threadedinto head II and the screw 38 bears against a strong compressed spring38 and is provided at one end with a lock nut 40. Adjustment of screw 38varies the tensioning of the spring 39. A cap 4U` secures the hollowscrew 38 in its position and protects it against damage. In the face ofthe piston 2 is provided a disc shaped shallow recess 62 into whichprojects the inner free peripheral end of the tube 36 in such a mannerthat at the outer end of the piston stroke the liquid which the pistonpushes out in front, ows in the direction of the arrows, the annularbounding wall of this recess 82 more or less enclosing in this positionthe inner tube end, and the distance a between the piston 2 and the edgeof the tubular part 38 decreasing gradually wherebyvdamping of the speedof the piston before its outer dead centre position is effected. Afterthe middle portion 4I has come into contact with the bolt I8, only avery small play remains between the parts 2 and 36. For facilitating thereturn movement of the piston a yielding valve 42 which is pressed by aspring to its seat and is opened towards the interior of the cylinder isprovided in the plate 3'I. Deformation of the spring 39 is onlyinconsiderable and immediately disappears. The provision of the springhas, however, the effect of reducing audibility of the noise .caused bythe impact.

'Ihe construction according to Fig. 6 may be further varied according toFig. 7 for a certain purpose, namely, in such a manner that a smallpiston pump is connected or substituted for the hydraulic shock dampingdevice. 'I'he device provided for this purpose contains a small pistonpump, the piston I8 of which replaces the abutment bolt I8 of Figs. 1and 6. The piston I8' which operates in cylinder 43 fixed and suitablypacked, as shown, in head I'I is pressed by a spring 44 into its outerposition and is limited in the latter by a screwed on nut 45. The liquidenters the cylinder of this pump during the in'- take stroke of piston 2through ports 46 which are afterward temporarily covered by piston I8'.The liquid in cylinder 43 is pressed by way of the non-return valve 41which is loaded by a sufficiently strong spring48, and flows through theopening in the nut 49 and through a pipe- 5I, which is connected to theouter end of the guide pump will also act as a shock damping device andsimultaneously forces out a quantity of fluid pretermined by thedimensions of the plunger I8', which has not been measured orl meteredand which serves as an average sample for ascertaining the condition ofthe quantity of fluid which has passed through the meter.

It is obvious that each pair of working pistons of the meter may haveunder the inuence of diierently set screws a dierent stroke. In order toobtain an independent movement of the two yokes 3, 3', the crank memberis preferably constructed in accordance with Figs. 8 and 9 whichsupplement Fig. 1. Two pistons 2 (in Fig. 9 only one piston is shown)are always connected by a yoke 3 or 3 formed with a yoke portion 4a orla; respectively. In these slots move with a slight play rollers 4, 4)mounted upon a pin 5, said pin being inserted into the crank arm 8,which latter is arranged rotatable about a bolt 52 and adjustablerelative to the second crank ann 8 also on said bolt 52. This secondcrank arm 8' is arranged rotatable about the pin 6 the Y axis of whichpreferably coincides with the axis of the whole meter. The pin 52 formedas a bolt permits free pivotal movement between arms 8 and 8 so that thelength of the stroke of one set of pistons may be different than thestroke of the other set of pistons. By this arrangement a variableradius of the path described by the axis of the rollers 4, 4' isattained. The radius varies in the course of each quarter revolution andits run is periodical. With this construction independence of themovement of one yoke of that of the other is possible within widelimits, andmoreover, the shocks occurring with-other constructions inwhich the rollers are fixed upon an arm of non-varying radius and aconsiderable play loccurs, between the rollers and the cross slides, areavoided. All described arrangements and initial parts constituting awhole aim at the same object of obtaining a constantly maintained -tothe axis of rotation, said valve having inlet and outlet openings in thelower seating surface thereofsaid inlet opening being connected by achannel with an opening in the side wall of said valve and said outletopening being connected by another channel with an opening in the upperseating surface of said valve, said valve being characterized by thefeature that the outer diameter d of the upper seating surface bears arelation to the outer diameter D of the lower seating surface accordingto the equation 2. A multi-piston meter comprising a. rotarydistributing valve and crank mechanism for driving said valve, a casingfor said valve, said valveA `having the shape of a body of rotation withtwo parallel seating surfaces disposed perpendicular to the axis oi.'rotation, said valve having inlet and outlet openings in the lowerseating surface thereof, said inlet opening being connected by a channelwith an opening in the side wall of said valve and said outlet openingbeing connected by another channel with an opening in the upper seatingsurface of said valve, said valve being characterized by the featurethat the outer diameter d of the upper seating surface bears a relationto the outer diameter D of the lower seating surface according to theequation f, 3 d- 1.Z5\/10D2 the body of the valve being divided into twoparts perpendicularly to the axis, and means for pressing said valveparts away from each other in sealing and axially resilient relation andfor rigidly connecting said valve parts to prevent twisting andtorsional movement.

3. In multi-piston meters, a rotatable distributor valve, saiddistributor valvehaving the shape of a; hollow truncated cone, thehollow base of said cone having an inlet, port and an outlet port, s'aidinlet port being connected to an opening in the wall of said cone andsaid outlet port being connected to an opening in the top of said cone,an elastically connected cylindrcal'member connected to the top of saidcone for connecting said outlet port to a fluid carrying duct, a casingconnected to the bottom of said rotatable distributor valve, fourmetering cylinders in said casing having pistons therein, a hydraulicand mechanical shock damping means positioned in said casing inalignment with said metering cylinders, said pistons and cylinders beingarranged in pairs, connecting means for connecting said pistons inpairs, crank means for engaging said piston connecting means, and meansfor operating said distributor Valve in accordance with the angularmovement of said crank means, said crank means being substantiallycoaxial with said distributor valve and means for completely separatingthe crank chamber from the liquid chambers of said distributor I valveand the ducts connected thereto.

4. In multi-piston meters, a rotatable distributor valve, a crankmechanism for driving said valve, said distributor valve having theshape of a hollow truncated con,the hollow base of said cone having aninlet port and an outlet port, said inlet ,port being connected to anopening in the wall of said cone and said outlet port being connected toan opening in the top of said cone, a cylindrical member slidablyconnected to the top of said cone for connecting said outlet port to afluid carrying duct, a casing connected to the bottom of said rotatabledistributor valve, a plurality of metering cylinders in said casing, apiston for each of said cylinders, means for connecting each of saidpistons to said crank l mechanism, a hydraulic and mechanical shockdamping" means positioned in said casing for limiting the stroke of eachof said pistons and means for adjusting said shock damping means forreducing the noise of-. the impact of said pistons thereon. l

5. In multi-piston meters, a rotatable distributor valve, a crankmechanism for driving said valve, said distributor valve having theshape of a hollow -truncated cone, the hollow base of said cone havingan inlet port and an outlet port, said inlet port being connected to anopening in the wall of said cone and said outlet port being connectedVto an opening in the top of said cone, a cylindrical member slidablyconnected to the top of said cone for connecting said outlet port to afluid carrying duct, a casing connected valve in accordance with theangular movement of said crank means, said crank means beingsubstantially coaxial with said distributor valve.

6. In multi-piston meters, a rotatable distributor valve, a crankmechanism for driving said valve, said distributor valve having theshape of a hollow truncated cone, the hollow base oi said cone havingan, inlet port and an outlet port, said inlet port being connected to anopening in the wall of said cone and said outlet port being connected toan opening in the top of said cone, a cylindrical member slidablyconnected to the top of said cone for connecting said outlet port to auid carrying duct, a casing connected to the bottom of said rotatabledistributor valve, i'our metering cylinders in said casing, a piston forI each of four cylinders, a hydraulic and mechanical shock damping meansfor each of said pistons, said pistons and cylinders being arranged inpairs, connecting means for connecting said pistons in pairs, said crankmechanism including crank means for engaging said piston connectingmeans and means for operating said distributor valve in accordance withthe angular movement of said crank means, said crank means beingsubstantially coaxial with said distributor valve and means forcompletely separating the crank chamber from the liquid chambers of saiddistributor valve and the ducts connected thereto.

7. In multi-piston meters, as set forth in claim l, a casing connectedto the bottom of said valve casing, a plurality of cylinders in saidlast casing, pistons for said cylinders, said pistons being connected tosaid crank mechanism. hydraulic and mechanical shock damping meanspositioned in said last casing in alignment with each of said meteringcylinders for limiting the movement of said pistons and means foradjusting said shock damping means..

8. In multi-piston meters, as set forth in claim 1, a casing connectedto the bottom of said valve FRAN'IISEK HEJDUK. JAN NEUMANN.

